2.1. adjust the LogDir, MailServer and ScriptDir values to your local settings

3. insert this monitor process in chore
This monitor process needs to be placed after every process that you would like to monitor.

How does it work?
Every process, after execution, returns a global variable "ProcessReturnCode", and that variable can be read by a process running right after in a chore.
The above process checks for that return code and pipes it to the mail script if it happens to be different from the normal exit code.

If you have a lot of processes in your chore, you will probably prefer to use the ExecuteProcess command and the check return code over a loop. That method is explained here.